Conventional ice makers typically provide an ice tray including a plurality of compartments that are filled with water and frozen to form ice cubes. A water supply is typically in fluid communication with at least one of the compartments of the ice tray. Often weirs, slots or gaps are provided between adjacent compartments in the tray so that water flows from a filled compartment into an adjacent compartment to fill the ice tray.
Typically, ice makers use a timer controlled valve on the water supply to determine the level of water in the compartments. This method of controlling water level suffers from a number of limitations. For one, the flow rates of household water supplies vary in response to load changes. For example, toilet flushes and lawn watering can substantially affect water flow rate in a house. Additionally, flow rates may change over time as mineral deposits in water and collect in the pipes restricting the water flow. The fluctuations in flow rates for a house mean that the amount of water filling an ice tray may significantly vary from cycle to cycle despite the accurate measurement of a fill time period. These variations affect the quantity of ice produced by an ice maker.
Problems with accurate water fills also affect the quality of the ice harvested. In many ice makers, a temperature sensor is placed in one compartment of the ice tray and the ice is harvested upon the sensed temperature in that compartment reaching a predetermined temperature that corresponds to the water in the compartment being adequately frozen. If the compartment in which the temperature sensor is located is only partially filled, then the ice harvest cycle may be initiated before the water has adequately frozen in the other ice tray compartments. This unequal filling of ice tray compartments may be caused by a floor settling so that the ice tray is tilted and no longer level. Ice harvests initiated upon detection of a predetermined temperature in a partially filled compartment results in the formation of ice having watery centers in the other compartments. This type of ice may break during the ice harvest and leave water in the compartments after the harvest. The water remaining in the compartments after ice harvest may cause compartment overfilling on the next fill cycle. If ice with a watery center does not break during the harvest cycle, it may break upon impact in the ice bin where the harvested ice is collected. Partially frozen ice breaking in the ice bin releases water that flows between other ice pieces and freezes them together. This may cause the ice to jam in the chute of an ice dispenser or to lump into a configuration that does not easily fit in a glass.
These problems make the accurate filling of the ice tray compartment in which the temperature sensor is located an important aspect of ice formation and harvesting.